ES2209159T3 - PROCEDURE FOR THE PREPARATION OF HETEROPHASIC PROPYLENE COPOLYMER. - Google Patents

Abstract

The invention relates to a heterophasic propylene copolymer having an elastic modulus of 420 MPa or less, including: i) a semi-crystalline propylene: ethylene: and optionally another {al} -olefin polymer as matrix; ii) an elastomeric ethylene: ethylene and optionally another {al} -olefin copolymer.

Description

Procedure for the preparation of copolymer of heterophasic propylene.

The present invention relates to a process to prepare heterophasic polypropylene copolymers and, in concrete, heterophasic polypropylene copolymers that are soft, they have good impact resistance at low temperatures, Good heat sealing properties and good properties Optical

Traditionally, the polymers in which it they want as low hardness properties, and therefore under module tensile strength, as well as good impact resistance to low temperatures, have been prepared from polychloride of soft vinyl (PVC). However, because the products of PVC cause environmental problems due to emissions from chlorinated organic compounds during combustion, there are currently a tendency to replace PVC with other polymers. As an alternative to PVC polymers, they have been used polypropylene polymers, since it is known that such polymers have adequate resistance to heat and chemical products, as well as attractive mechanical properties.

It is known that certain polypropylene copolymers Heterophasic are especially suitable as soft polymers. When soft heterophasic polypropylene copolymers are produced it is common to prepare a polypropylene copolymer matrix with a comonomer content to obtain the desired properties. To achieve lower hardness, you can then add a amorphous elastomeric component to the copolymer matrix.

For example, in the European patent document EP-A-0373660 (Himont Incorporated), a composition of propylene polymer having Good transparency and low temperature impact resistance enhanced, comprising 70 to 98% crystalline copolymer of propylene with ethylene and / or other α-olefin and an elastomeric propylene-ethylene copolymer.

In the European patent document EP-A-0416379 (Himont Incorporated) a thermoplastic olefin polymer having elastic properties, comprising a polymer fraction crystalline comprising, for example, a propylene copolymer with at least one α-olefin, a fraction semi-crystalline and 2 to 30% of an amorphous copolymer fraction of α-olefin and propylene, with or without diene.

In the two applications described above, For reasons of economy, the initial copolymer matrix can be produce in a reactor of suspended products better than in a gas phase reactor. The product of the phase reaction suspension expands suddenly to eliminate monomers without react and is transferred to a gas phase reactor in which additional reaction processes take place and the elastomeric component.

However, since the matrix component is prepared in the liquid phase, the comonomer content of the matrix and, therefore, the tensile strength module is limited. Comonomers such as ethylene and other α-olefins cause the polymers to swell during the reaction in the liquid phase reactor. When the reaction medium suddenly expands to remove the monomer reagents after polymerization of the matrix but before the transfer to the gas phase reactor, the morphology of the particles is destroyed and the bulk density of the powder becomes very low. This sticky material clusters into the walls of the sudden expansion tank and causes problems when transporting it to the gas reactor. These problems increase when the proportion of comonomers in the copolymer increases and, therefore, the softness of the copolymer is limited.
polymer.

Attempts to reduce stickiness or adhesion of the material in the sudden expansion tank by catalyst manipulation or by reducing xylene soluble fraction content have been successful limited, and, consequently, in order to obtain copolymers of soft polypropylene with a very high comonomer content, has traditionally it was necessary to use polymerization in gas phase

Surprisingly, it has been found that you can economically prepare soft polypropylene copolymers with low values of tensile strength module and content of high comonomer, since the sudden expansion of the mixture of matrix prepared in the liquid phase reactor (for example, a suspension product reactor) is not necessary, and can be Directly transfer the net reaction mixture from the liquid phase to the gas phase reactor. Since it is Eliminates the sudden expansion stage, there are no problems with the sticky material that adheres to the tank walls of expansion and, therefore, concentrations of higher comonomer and the properties of softness.

Therefore, from the point of view of a aspect, the invention provides a process for the preparation of a heterophasic polypropylene copolymer, which has a module of tensile strength of 420 MPa or less, comprising stages of:

i) produce a copolymer matrix Propylene semicrystalline: ethylene and, optionally, other α-olefin, which comprises 0.5 to 10% by weight of ethylene and, optionally, 5 to 12% by weight of the other α-olefin, in one or more slurry reactors and, optionally, in one or more gas phase reactors;

ii) followed by producing a copolymer elastomeric ethylene: propylene and, optionally other α-olefin, in the gas phase;

in which the phase reactor transfer liquid to the next gas phase reactor is performed without sudden expansion to eliminate unreacted monomer.

For the purposes of this application, the term copolymer encompasses polymers comprising two or more comonomers

When the polypropylene copolymer matrix semicrystalline comprises an α-olefin, in addition to ethylene and propylene, it comprises more preferably from 1 to 7% of ethylene by weight, most preferably from 1 to 5% in matrix and α-olefin weight additional 6 to 10% by weight of the matrix.

When the semicrystalline matrix component it is only an ethylene copolymer: propylene, ethylene comprises preferably from 3.5 to 8.0% by weight, more preferably from 4 to 7% by weight of the matrix.

The other α-olefin can be a mono or C 4-20 diene, and can be linear, branched or cyclic. The other α-olefin has preferably as structure H2 C = CHR, where R represents an alkyl group. Preferably, the α-olefin has between 4 and 8 carbon atoms and is most preferably 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene or 1-octene, especially 1-butene.

The xylene soluble fraction of the component of the matrix (XS) is preferably in the range 3 to 30%, most preferably 6 to 20%, by weight of the matrix component.

The elastomeric copolymer of propylene: ethylene and optionally another? -olefin can comprise any suitable proportion of propylene monomers, ethylene and optionally other α-olefins that of how an amorphous elastomeric copolymer resulted or semicrystalline / amorphous. Preferably, the elastomeric component It comprises a copolymer of only ethylene and propylene.

The amount of matrix component in the heterophasic copolymers of the invention is between 20 and 90%, preferably 60 and 90% by weight of the heterophasic copolymer. The amount of elastomeric copolymer may be in the range 10 at 80%, preferably 10 to 40% by weight of the heterophasic polymer. The elastomer component may comprise 95-5% by weight, preferably 95-20%, of crystalline phase and 5-95% by weight, preferably 5-80%, amorphous phase.

In one embodiment, it can be mixed with the heterophasic polymers of the invention from 5 to 40% by weight of elastomer or plastomer, based on the weight of the copolymer Heterophasic Adding varying amounts of elastomer or Plastomer to the heterophasic polymers of the invention, it can be further reduce the hardness or stiffness of the polymers, improve optical properties and increase resistance to impact at low temperatures. Among the suitable elastomers are include ethylene rubber: butene, terpolymeric rubber, but it is preferable ethylene rubber: propylene (EPR) English). The elastomer can also be added in the form of a monomer ethylene: propylene diene (EPDM). These Elastomers can be prepared by conventional processes and can be they can mix with the heterophasic polymers of the invention using standard mixing techniques.

The tensile strength module of the Heterophasic polymer of the invention is 420 MPa or less, but preferably it should be greater than 80 MPa, preferably greater 100 MPa More preferably, the modulus of resistance to traction should be in the range of 100 to 400 MPa, even more  preferably from 100 to 350 MPa and most preferably from 100 to 300 MPa

The xylene soluble fraction of the polymer final heterophasic (XS) is preferably between 20 and 60%, more preferably from 30 to 45%.

To ensure that heterophasic polymers have adequate impact properties, it is preferred that they can be Classify the polymers as ductile at 20 ° C.

Heterophasic polypropylene copolymers of the invention occur in a combination of at least one reactor of suspended products and at least one gas phase reactor connected directly together, thus avoiding the stage of sudden expansion and, therefore, the inconveniences that have been discussed above when high content products are produced of comonomers, using a sudden expansion stage.

People skilled in the art will determine easily suitable preparation methods; among them They include the following, although the relationship is not limiting:

TO.

Produce the matrix of polypropylene copolymer containing ethylene, and optionally another higher α-olefin, in one or two product reactors in suspension; then feed the mixture of product reactor in suspension to a gas phase reactor, and produce in the gas phase reactor (GPR) English) an elastomeric copolymer.

B.

Produce the matrix of polypropylene copolymer containing ethylene, and / or others upper α-olefins, in two stages; in first place in one or more reactors of suspended products and then in a gas phase reactor, using a feed direct from the reactor of suspended products to the GPR, and then feed the reaction mixture to a second GPR and continue the polymerization to produce an elastomer similar to the case TO.

C.

Produce a heterophasic polymer as described in A or B and then produce more elastomeric copolymer in gas phase reactors additional.

D.

Produce a heterophasic polymer as described in A, B or C, and then mix it with an adequate amount of elastomer (for example, EPR, EPDM) or plastomer, prepared by techniques conventional.

Experts, specialized in technique, they can adapt comonomer feeds to different reactors to produce a polymer with the properties that are desired, and can easily determine the amounts of comonomer

In the reactor of suspended products, the Propylene acts not only as a monomer for polymerization, but also as a diluent. The products stage in suspension, which preferably runs in a circuit reactor closed, it is carried out by feeding, at least one stage of suspension polymerization, a reaction mixture containing 50-95% by weight of propylene, 1-10% by weight of ethylene and 0-40% by weight of another α-olefin, and a catalyst system, while that the olefin polymerization is maintained at a temperature below 75 ° C. When two or more reactors are used suspended products are preferably circuit reactors closed, and fed with the same mixture of comonomers as in the  case of an individual suspension product reactor. From the suspension product reactor, the reaction mixture is feeds directly to one or more gas phase reactors.

When a gas phase reactor is used, the gas phase polymerization stage is carried out preferably adding 0-40% by weight of propylene, 1-30% by weight of ethylene, 0-10% by weight of another α-olefin of the feed mixture. Preferably, the ratio of gases used in the mixture of feed in the preparation of the elastomer component is C2 / (total monomer) (mol / mol): between 0.05-0.5, preferably 0.2-0.5 and the ratio C4 / (monomer total) is greater than or equal to 0.15. In this case the phase reactor Soda is mainly used to produce the component of elastomeric copolymer, which preferably comprises 5 to 40% by weight, more preferably 10 to 40% by weight of the polymer heterophasic of the invention.

When a gas phase reactor is used additionally, the first gas phase reactor is used mainly to produce more matrix component. In this case, the ethylene feed to the first gas phase reactor it is preferably 15% by weight, more preferably 1 to 8% in weight. The gas phase polymerization stage is continued preferably in the second gas phase reactor, adjusting the gas concentrations at: 60-90% by weight for propylene, 5-40% by weight for ethylene and 0-10% by weight of others α-olefins. Such concentrations produce more semicrystalline and amorphous elastomeric copolymer in the product produced in the first stage polymerization stage soda.

In one embodiment, hydrogen can be added to the liquid and gas phase, one of them or both, to control the molecular weight of the polymer of the invention. The use of hydrogen in the polymerization of olefins is somewhat conventional and It will be easily applied by people specialized in technique.

The polymerization in the products phase in suspension can be carried out at temperatures below 75 ° C, preferably 60-65 ° C, and at varying pressures between 30 and 90 bars, preferably between 30 and 70 bars. The polymerization is preferably carried out under such conditions that 20-90% by weight, preferably 40-80% by weight of the polymer is polymerized in the reactor or liquid reactors. The time of stay can be between 15 and 120 minutes.

The gas phase polymerization step is carried out by transferring the reaction mixture of the phase of suspended products directly to the gas phase, without remove unreacted monomers, preferably at pressures greater than 10 bars. The reaction temperature used it will generally be in the range of 60 to 115 ° C, preferably from 70 to 110 ° C. The reaction pressure will be greater than 5 bars, and preferably it will be in the range of 10 to 25 bars, and the time  The stay will generally be 0.1 to 5 hours. Since the monomers that have not reacted from the product phase in suspension are transferred to the gas phase, it is important establish how much unreacted monomer has been transferred in order to allow a simple determination of how much additional monomer must be added to the gas phase. Such measures can be achieved. by simple gas phase chromatography, allowing the maintenance of appropriate comonomer concentrations.

The liquid medium of the first phase reactor it can function as a means of cooling the fluid bed in the gas phase reactor, when it evaporates in there.

Preferably, a circuit reactor is used closed as said reactor of suspended products, although they can also use other types of reactors, such as a reactor Deposit According to another embodiment, said phase of products in suspension is carried out in two product reactors in suspension, preferred but not necessarily in two reactors of closed circuit. In this way, you can easily control the comonomer distribution. When copolymerization is continued in a gas phase reactor or reactors, it can be increased additionally the comonomer content. Consequently, you can  tailor the matrix polymer, adjusting the proportions of comonomers in different reactors.

The elastomer can be produced in the polymer heterophasic of the invention in one or more phase reactors gaseous, or mixed in the final polymer using procedures mixing standard Controlling the quantity and composition of elastomer component in the final polymer, the  properties, for example, the optical and impact properties and the softness.

The polymerization can be carried out using any olefin polymerization catalyst standard, and those are well known to specialized people in the technique Preferred catalyst systems comprise a normal stereospecific catalyst Ziegler-Natta, metallocene catalysts and other organometallic catalysts or coordination. An especially preferred catalyst system It is a high-performance Ziegler-Natta catalyst, which has a catalyst component, a cocatalyst component, optionally an external giver. The catalyst system can contain, in this way, a titanium compound and a donor compound of electrons supported in an activated magnesium dichloride, a trialkylaluminum compound as activator and a donor compound of electrons

A more preferred catalyst system is a metallocene catalyst that has a bridge structure that provides high stereoselectivity and that is impregnated in a vehicle as an active complex.

Suitable catalyst systems are described, for example, in patent documents FI 88047, EP 491566, EP 586390 and WO98 / 12234, which are incorporated herein as references.

Soft propylene copolymer products which have low hardness or stiffness, high impact resistance at low temperatures and that should optionally have good capacity Sealing and transparency, can be used in a wide variety of Applications, such as films, molded parts, sheets, caps, bottles, fibers, tubes, foams, sheaths and cable insulators, and Compounds (flame retardants and other loading compounds high).

Examples

A combination of a reactor of suspended products and gas phase reactors to produce the soft heterophasic polypropylene copolymers of the present invention

The following analytical techniques were used To test the synthesized polymers:

Melt flow rates were measured (MFR) under a load of 2.16 kg and at 230 ° C, according to ISO 1133.

Comonomer contents (ethylene) were measured and butene) by infrared transform spectroscopy of Fourier (FTIR), calibrated with nuclear magnetic resonance spectroscopy (NMR) in English).

Melting temperatures (peak temperatures) were measured by differential scanning calorimetry (DSC, by its acronym in English), using an increasing speed of temperature of 10ºC / minute.

Tensile strength (resistance to creep point traction) was measured according to ISO 572-2 (crosshead speed = 50 mm / min)

The tensile modulus was measured according to ISO 572-2 (crosshead speed = 1 mm / min)

The flexural strength module was measured according to ISO 178.

The relative impact resistance, called also notch sensitivity, Izod, was measured according to ISO 180 / 1A.

The impact on the weight that falls instrumented was measured according to ISO 6603-2.

Film rehearsals were measured on a 40 micrometer thick film, produced in a line of film casting (Collin), at melting temperature of 270 ° C and cold roller temperature of 30 ° C.

The film module (secant module of elasticity at a deformation of 1%) was measured according to ISO 1184 (ASTM D882) (crosshead speed = 5 mm / min).

Turbidity was measured according to ASTM D 1003 and the gloss at 60 ° C according to ASTM D 523.

Hot stamping properties (heat sealed) were measured from an ABA film of 25 micrometers (central layer of PP homopolymer and as a layer superficial the terpolymer of PP investigated as to its capacity for heat closing). The sealing time was 0.1 s and the pressure of 3 bar. Heat seal resistance = peel off the seal using 25.41 mm width film strips; it was measured with a universal Instron test equipment (speed of transverse head = 100 mm / min).

Examples 1-5

The polymerizations were carried out in a 5 dm3 reference scale reactor, under stirring. I know produced a matrix in liquid propylene at 60 ° C in the first stage. After the desired time of 1 hour of polymerization, it was reduced slowly the pressure up to 6 bar, and polymerization was continued In the gas phase. In the gas phase, copolymers were polymerized semicrystalline and amorphous at 75 ° C in the matrix from 1 to 1.5 h.

The catalyst used, whose activity was 35 kg PP / g cat h, was prepared according to the patent document WO98 / 12234.

The polymerization conditions and the Polymer properties are presented in Table 1.

In example 5, the pressure was quickly reduced until reaching atmospheric pressure, simulating the operation of a sudden expansion tank. Polymerization was not possible in gas phase and only matrix component was produced.

TABLE 1

one

two

Example 6 (comparative)

A circuit reactor combination was used Closed to pilot scale and a gas phase reactor to produce soft heterophasic polypropylene copolymers. In the reactor closed-circuit propylene, ethylene and hydrogen were fed. The polymerization temperature in the closed circuit reactor It was 70 ° C. The temperature in the GPR was 70 ° C. The pressure on the closed circuit reactor was 40 bar and in the phase reactor 10 bar soda. The catalyst used was as in the examples 1 to 5, giving an activity of 35 kg PP / g cat h.

The random copolymer produced in the reactor of closed circuit gave an ethylene content of 3.5-3.7% by weight and a fraction soluble in xylene (XS) = 9% by weight.

When this copolymer suddenly expanded several problems arose due to adhesions in the deposit of expansion, which made transportation to the GPR impossible.

Example 7

A combination of a circuit reactor was used Closed to pilot scale and a gas phase reactor to produce soft heterophasic copolymer. The random copolymer of Ethylene: Propylene was produced in the closed circuit reactor. The The ethylene content of the polymer was 4.2% by weight and the XS was 9% by weight.

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This reactor mixture transported directly to the gas phase reactor. They fed more ethylene and propylene, using the C2 / (total monomer) gas ratio of 0.35 mol / mol in the GPR and an impact copolymer was produced.

The final heterophasic polymer had a content ethylene of 9.5% and an XS fraction of 25%.

To further improve the softness and properties of impact, 15% PE copolymer of very low density was mixed (VLDPE), obtaining the following properties:

Table + VLDPE (15%) Module tensile strength, MPa 590 420 Impact on falling weight at -20ºC, type of failure ductile ductile Weight impact falling at -40 ° C, type of failure brittle / ductile-brittle ductile Module of the film, MPa 280 210

Example 8

A copolymer was produced in pilot reactors chance of propylene with a high ethylene content; in the circuit closed, a random copolymer with a content of lower ethylene The reaction mixture was transported to the reactor of gas phase and more ethylene was fed.

To further improve the softness and properties of impact, 20% PE copolymer of very low density was mixed (VLDPE) (Eact 2M011 from DEX plastomers, density 0.88), obtaining the following properties:

Property + VLDPE (20%) C2 in the first stage,% in weight 3.8 XS of the first stage,% in weigh 6.7 Total content of ethylene,% by weight 7.9 26.5 Module tensile strength, MPa 380 280 Impact on falling weight at 0 ° C, type of failure ductile ductile Weight impact falling at -20ºC, type of failure brittle ductile Module the movie, MPa 220 190 Turbidity of the movie, % 0.5 2.2 Shine the movie, % 150 140

Example 9

A pilot scale reactors were produced heterophasic polypropylene; in the closed circuit, there was a random copolymer; this reactor mixture was transported directly to the gas phase reactor, where they fed more ethylene and propylene, using a proportion of gases, C2 / 0.35 total monomer.

First stage: C2,% in weight 4.2 XS,% in weight 7.4 Product final: C2,% in weight 19.3 XS,% in weight 40 Resistance Module traction, MPa: 360 Impact on falling weight at -20ºC, type of fault ductile Impact on falling weight at -40 ° C, type of failure ductile Izod impact, at -30ºC, KJ / m2 22 Movie module, MPa 220 Turbidity, 40 movie \ mum 7.6

Example 10

A pilot plant managed in a way was used Continues to produce PP copolymer with good properties of impact and slip. The plant comprises the systems of catalyst, alkyl, donor, propylene and ethylene feed, a  prepolymerization reactor, a closed circuit reactor and two Gaseous fluid bed phase reactors (GPR) English).

The catalyst, the alkyl, the donor and the Propylene is fed to the prepolymerization reactor. The polymer suspension of the polymerization reactor is fed to a closed circuit reactor, which is also fed hydrogen, ethylene and additional propylene.

The polymer suspension of the circuit reactor closed, along with more hydrogen and propylene are fed to the first GPR The polymer from the first GPR is fed to the second GPR The second GPR is fed ethylene, some hydrogen and more propylene The polymer formed and the unreacted propylene are they separate after their extraction from the second GPR.

The catalyst used is a ZN catalyst (Ziegler-Natta) very active and stereospecific, prepared according to US Pat. number 5,234,879. Before being fed to the prepolymerization reactor, the catalyst is contacted with triethylaluminum (TEA) and dicyclopentyldimethoxysilane (DCPDMS) (the Al / Ti ratio is 150 and Al / Do, 10 (mol)).

The catalyst is fed according to the document of U.S. Patent UU. number 5,385,992 and is dragged into the reactor of closed circuit with propylene. The prepolymerization reactor is operates at a pressure of 51 bar, a temperature of 20 ° C and an average catalyst residence time of 7 minutes.

The closed circuit reactor is operated at a pressure of 50 bar, a temperature of 75 ° C and a time of Average catalyst stay of 1 hour. The MFR (2.16 kg, 230 ° C) of the random polymer of PP produced in the closed circuit is set to 7 controlling the hydrogen feed. The content ethylene is adjusted to 3.5% (weight percentage by weight), using ethylene feed as a control medium.

The polymer suspension of the circuit reactor Closed is transferred to the first GPR. The first GPR reactor is made operate at a total pressure of 29 bar and at a partial pressure of 21 bar propylene. The working temperature is 80ºC and the time Average catalyst stay, 1.5 h. MFR (2.16 kg, 230 ° C) of the random PP polymer taken out of the GPR conforms to 10, using hydrogen partial pressure. Ethylene content set to 2% (weight percentage by weight) by adjusting the production distribution between reactors.

The polymer that comes from the first GPR is transferred to the second GPR. The second GPR is operated at a total pressure of 10 bar and at a monomer partial pressure of 7 Pub. The working temperature is 80ºC and the time of stay catalyst average 1.5 h. The MFR (2.16 kg, 230 ° C) of PP copolymer taken out of the GPR is set to 7 by pressure partial hydrogen. The ethylene content is set at 10% (weight percentage by weight) by adjusting the partial pressure of ethylene and controlling the distribution of production between reactors

The desired properties are achieved with a 1% production distribution in the prepolymerization, 40% in the closed circuit reactor, 40% in the first GPR and 19% in the second GPR.

Example 11

A pilot plant managed in a way was used continues to produce very soft PP copolymer. Plant comprises catalyst, alkyl, feed systems donor, propylene and ethylene, a prepolymerization reactor, a closed circuit reactor and a bed gas phase reactor fluid (GPR).

The catalyst, the alkyl, the donor and the Propylene was fed to the prepolymerization reactor. The polymer suspension of the polymerization reactor was fed to a closed circuit reactor, which was also fed hydrogen, ethylene and additional propylene.

The polymer suspension from the reactor closed circuit, along with more hydrogen, ethylene and propylene They fed to the GPR. The polymer formed and the monomers without react were separated after their extraction from the GPR.

The catalyst used was a ZN catalyst (Ziegler-Natta) highly active and stereospecific, prepared according to the patent document of USA No. 5,234,879. Before being fed to the reactor of prepolymerization, the catalyst was contacted with triethylaluminum (TEA) and dicyclopentyldimethoxysilane (DCPDMS) (the Al / Ti ratio was 150 and Al / Do, 10 (mol)).

The catalyst was fed according to the document of U.S. Patent UU. number 5,385,992 and was dragged into the reactor of closed circuit with propylene. The prepolymerization reactor is operated at a pressure of 51 bar, a temperature of 20 ° C and an average catalyst residence time of 7 minutes.

The closed circuit reactor was operated at a pressure of 50 bar, a temperature of 75 ° C and a time of Average catalyst stay of 1 hour. The MFR (2.16 kg, 230 ° C) of the random polymer of PP produced in the closed circuit it was adjusted to be 4, by feeding hydrogen. The ethylene content was adjusted to 3.8% (weight percentage in weight), controlling the ethylene feed.

The polymer suspension from the reactor closed circuit was transferred to the first GPR. The first reactor GPR was operated at a total pressure of 29 bar and at a pressure 21 bar propylene partial. The working temperature was 80ºC and the average residence time of the catalyst, 1.2 h. The MFR (2.16 kg, 230 ° C) of the random PP polymer taken from the GPR is set to 2.5, adjusting the partial pressure of hydrogen. The ethylene content was set at 8% (weight percentage in weight), adjusting the production distribution between the reactors and the partial pressure of ethylene.

The desired properties were achieved with a 1% production share in prepolymerization, 45% in closed circuit reactor and 55% in the GPR.

Example 12

A pilot plant managed in a way is used Continues to produce PP copolymer with good properties of impact and slip. The plant comprises the systems of catalyst, alkyl, donor, propylene and ethylene feed, a  prepolymerization reactor, a closed circuit reactor and two Gaseous fluid bed phase reactors (GPR) English).

The catalyst, the alkyl, the donor and the Propylene is fed to the prepolymerization reactor. The polymer suspension of the prepolymerization reactor is fed to a closed circuit reactor, which they also feed hydrogen, ethylene and additional propylene.

The polymer suspension of the circuit reactor closed, along with more hydrogen and propylene are fed to the first GPR The polymer from the first GPR is fed to the second GPR The second GPR is fed ethylene, some hydrogen and more propylene The polymer formed and the unreacted propylene are they separate after their extraction from the second GPR.

The catalyst used is a ZN catalyst (Ziegler-Natta) very active and stereospecific, prepared according to US Pat. number 5,234,879. Before being fed to the prepolymerization reactor, the catalyst is contacted with triethylaluminum (TEA) and dicyclopentyldimethoxysilane (DCPDMS) (the Al / Ti ratio is 150 and Al / Do, 10 (mol)).

The catalyst is fed according to the document of U.S. Patent UU. number 5,385,992 and is dragged into the reactor of closed circuit with propylene. The prepolymerization reactor is operates at a pressure of 51 bar, a temperature of 20 ° C and an average catalyst residence time of 7 minutes.

The closed circuit reactor is operated at a pressure of 50 bar, a temperature of 75 ° C and a time of Average catalyst stay of 1 hour. The MFR (2.16 kg, 230 ° C) of the random polymer of PP produced in the closed circuit It adjusts to 7 through hydrogen feed. Is controlled the ethylene content is 3.5% (weight percentage by weight), by feeding ethylene.

The polymer suspension of the circuit reactor Closed is transferred to the first GPR. The first GPR reactor is made operate at a total pressure of 29 bar and at a partial pressure of 21 bar propylene, at a working temperature of 80ºC and a Average catalyst residence time of 1.5 h. Is controlled that the MFR (2.16 kg, 230 ° C) of the PP random polymer taken from the GPR be 10, by hydrogen partial pressure. Is controlled the ethylene content is 2% (weight percentage by weight) through the distribution of production between the reactors.

The polymer that comes from the first GPR is transferred to the second GPR. The second GPR is operated at a total pressure of 10 bar and a partial pressure of monomers of 7 bar, at a working temperature of 80ºC and a time of stay 1.5 hr catalyst average. It is controlled that the MFR (2.16 kg, 230 ° C) of the random polymer of PP taken from the GPR be 7, by means of partial pressure of hydrogen. It is controlled that the content of ethylene be 10% (weight percentage by weight) through pressure partial ethylene and controlling the distribution of production between reactors

The desired properties are achieved with a 1% production distribution in the prepolymerization, 40% in the closed circuit reactor, 40% in the first GPR and 19% in the second GPR.

Example 13

It uses a pilot plant managed in a way Continues to produce PP copolymer with good properties of impact and slip. The plant comprises the systems of feeding of a catalyst, alkyl, donor, propylene and ethylene,  a prepolymerization reactor, a closed circuit reactor and two fluid bed gas phase reactors (GPR) in English).

The catalyst, the alkyl, the donor and the Propylene is fed to the prepolymerization reactor. The polymer suspension of the polymerization reactor is fed to a closed circuit reactor, which is also fed hydrogen, ethylene and additional propylene.

The polymer suspension of the circuit reactor closed, along with more hydrogen and propylene are fed to the first GPR The polymer from the first GPR is fed to the second GPR The second GPR is fed ethylene, some hydrogen and more propylene The polymer formed and the unreacted propylene are they separate after their extraction from the second GPR.

The catalyst used is a ZN catalyst (Ziegler-Natta) very active and stereospecific, prepared according to US Pat. number 5,234,879. Before being fed to the prepolymerization reactor, the catalyst is contacted with triethylaluminum (TEA) and dicyclopentyldimethoxysilane (DCPDMS) (the Al / Ti ratio is 150 and Al / Do, 10 (mol)).

The catalyst is fed according to the document of U.S. Patent number 5,385,992 and is dragged into the reactor of closed circuit with propylene. The prepolymerization reactor is operates at a pressure of 51 bar, a temperature of 20 ° C and an average residence time of the catalyst amounting to 7 minutes

The closed circuit reactor is operated at a pressure of 50 bar, a temperature of 75 ° C and a time of Average catalyst stay of 1 hour. It is controlled that the MFR (2.16 kg, 230 ° C) of the random PP polymer produced in the circuit closed be 7, by feeding hydrogen. Is controlled the ethylene content is 3.5% (weight percentage by weight), by feeding ethylene.

The polymer suspension of the circuit reactor Closed is transferred to the first GPR. The first GPR reactor is made operate at a total pressure of 29 bar and at a partial pressure of 21 bar propylene, at a working temperature of 80ºC and a Average catalyst residence time of 1.5 h. Is controlled that the MFR (2.16 kg, 230 ° C) of the PP random polymer taken from the GPR be 10, by hydrogen partial pressure. Is controlled the ethylene content is 2% (weight percentage by weight) through the distribution of production between the reactors.

The polymer that comes from the first GPR is transferred to the second GPR. The second GPR is operated at a total pressure of 10 bar and a partial monomer pressure of 7 bar, at a working temperature of 80 ° C and an average catalyst residence time of 1.5 h. The MFR (2.16 kg, 230 ° C) of the random PP polymer taken from the GPR is adjusted to 7, using the hydrogen partial pressure. The ethylene content is adjusted to 10% (weight percentage by weight) through the partial pressure of ethylene and controlling the distribution of production between
reactors

The desired properties are achieved with a production distribution comprising: 1% in prepolymerization, 40% in the closed circuit reactor, 40% in the first GPR and 19% in the second GPR.

Example 14

A pilot plant managed in a way was used continues to produce very soft PP copolymer. Plant comprises catalyst, alkyl, feed systems donor, propylene and ethylene, a prepolymerization reactor, a closed circuit reactor and a bed gas phase reactor fluid (GPR).

The catalyst, the alkyl, the donor and the Propylene was fed to the prepolymerization reactor. The polymer suspension of the polymerization reactor was fed to a closed circuit reactor, which was also fed hydrogen, ethylene and additional propylene.

The polymer suspension of the circuit reactor closed, along with more ethylene, hydrogen and propylene it They fed the GPR. The polymer formed and the monomers without react were separated after their extraction from the GPR.

The catalyst used was a ZN catalyst (Ziegler-Natta) very active and stereospecific, prepared according to US Pat. number 5,234,879. Before being fed to the prepolymerization reactor, the catalyst is contacted with triethylaluminum (TEA) and dicyclopentyldimethoxysilane (DCPDMS) (the Al / Ti ratio is 150 and Al / Do, 10 (mol)).

The catalyst was fed according to the document of U.S. Patent UU. number 5,385,992 and was dragged into the reactor of closed circuit with propylene. The prepolymerization reactor is operated at a pressure of 51 bar, a temperature of 20 ° C and an average catalyst residence time of 7 minutes.

The closed circuit reactor was operated at a pressure of 50 bar, a temperature of 75 ° C and a time of Average catalyst stay of 1 hour. It was checked that the MFR (2.16 kg, 230 ° C) of the random PP polymer produced in the circuit closed off 4, by feeding hydrogen. It was controlled that the ethylene content be 3.8% (weight percentage in weight), by feeding ethylene.

The polymer suspension of the circuit reactor Closed was transferred to the first GPR. The first GPR reactor was made operate at a total pressure of 29 bar and at a partial pressure of 21 bar propylene, at a working temperature of 80ºC and a Average catalyst residence time of 1.2 h. It was controlled that the MFR (2.16 kg, 230 ° C) of the PP random polymer taken from the GPR out 2.5, by hydrogen partial pressure. It was controlled that the ethylene content be 8% (weight percentage by weight), through the distribution of production between the reactors and the pressure Partial ethylene

The desired properties are achieved with a 1% production share in prepolymerization, 45% in closed circuit reactor and 55% in the GPR.

To produce a PP copolymer even more soft, the polymer from the GPR could have been transferred to another GPR, having even a higher ethylene partial pressure in the second GPR.

Examples 15-18

A combination of circuit reactors was used closed and gas phase, pilot scale, to produce propylene copolymers for films. They were fed to the reactor closed circuit propylene, ethylene, butene and hydrogen. The polymerization temperature was 60 ° C in both reactors. The pressure in the closed circuit reactor was 35 bar and in the reactor gas phase, 15 bar. The catalyst used was a prepolymerized catalyst, prepared according to the documents of Finnish patents numbers FI 70028 and FI 86472, whose activity It was 35 kg PP / g cat h.

The polymer produced, together with the monomers unreacted, they were sent directly to the gas phase reactor, and the polymerization was completed there. The conditions of Polymerization are presented in the following table.

3

The properties of copolymer products obtained in the gas phase reactor are presented in the table next.

4

Example 19

The polymerization was carried out as in the Examples 15 to 18, using a catalyst prepolymerized in wax form, prepared according to the Finnish patent document 88047. The polymerization conditions are presented in the table next.

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Example 19 Closed circuit Gas Temperature, ºC 60 74 Pressure, Pub 38 fifteen Cup of production, kg / h 11.0 8 Propylene feed, kg / h 2. 3 - Feeding of ethylene, kg / h 0.25 - Butene feed, kg / h 7.3 - Stay time, min 114 120 Density apparent volume, g / dm3 0.35

The copolymer obtained had the properties shown in the following table.

Example 19 MFR2 (g / 10 min) 4.9 Ethylene content (% by weight over weight) 3.5 Butene content (% by weight over weight) 12.4 Melting Temperature (ºC) 120 Tensile strength (MPa) 14.2 Tensile strength module (MPa) 360 Resistance to relative impact (Izod) (sensitivity to the 54 notch) (kJ / m2) Secant module at 1% (MPa) 190 Turbidity (%) 1.3 Brightness, 60 152 Resistance to heat sealing: temperature / resistance from sealed

Claims (24)

1. A process for the preparation of a heterophasic polypropylene copolymer, which has a module tensile strength of 420 MPa or less, comprising stages of: i) produce a copolymer matrix Propylene semicrystalline: ethylene and, optionally, other α-olefin, which comprises 0.5 to 10% by weight of ethylene and, optionally, 5 to 12% by weight of the other α-olefin, in one or more reactors of suspended products and, optionally, one or more reactors of gas phase; Y ii) followed by producing a copolymer elastomeric propylene: ethylene and, optionally other α-olefin, in the gas phase; in which the phase reactor transfer liquid to the next gas phase reactor is performed without sudden expansion to eliminate unreacted monomer. 2. A process according to claim 1, in the that said matrix comprises 0.5 to 10% by weight of ethylene and 5 to 12% by weight of the additional α-olefin. 3. A process according to claim 2, in the that said matrix comprises 1 to 7% by weight of ethylene and 6 to 10% in weight of the additional α-olefin. 4. A process according to any one of the claims 1 to 3, wherein said matrix comprises a additional α-olefin, which has 4 to 8 carbons 5. A process according to claim 4, in the that said matrix comprises 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene or 1-octene. 6. A process according to claim 5, in the that said matrix comprises 1-butene. 7. A process according to claim 1, in the that said matrix component is only a copolymer of ethylene: propylene. 8. A process according to claim 7, in the that said matrix component comprises 3.5 to 8% by weight of ethylene. 9. A process according to claim 8, in the that said matrix component comprises 4 to 7% by weight of ethylene. 10. A process according to any one of the claims 1 to 9, wherein the xylene soluble fraction (XS, by its acronym in English) of the matrix component is in the range 3 to 30% by weight. 11. A process according to claim 10, in the that the xylene soluble fraction (XS) of the matrix component It is in the range 6 to 20% by weight. 12. A process according to any one of the claims 1 to 11, wherein said matrix component form 20 to 90% by weight of the heterophasic polymer. 13. A process according to claim 12, in the that said matrix component forms 60 to 90% by weight of the heterophasic polymer 14. A process according to any one of the claims 1 to 13, wherein said elastomeric component It comprises an additional alpha-olefin. 15. A process according to any one of the claims 1 to 13, wherein said elastomeric component is only a copolymer of propylene: ethylene. 16. A process according to any one of the claims 1 to 15, wherein said elastomeric component form 10 to 80% by weight of the heterophasic polymer. 17. A process according to claim 16, in the that said elastomeric component forms 10 to 40% by weight of the heterophasic polymer 18. A process according to any one of the claims 1 to 17, wherein the resistance module Polymer traction is in the range 100 to 400 MPa. 19. A process according to claim 18, in the that the tensile strength module of the polymer is in the range 100 to 300 MPa. 20. A process according to any one of the claims 1 to 11, wherein the xylene soluble fraction (XS) of the heterophasic polymer is between 20 and 60%. 21. A process according to claim 20, in the that the xylene soluble fraction (XS) of the heterophasic polymer It is between 30 and 45%. 22. A process according to any one of the claims 1 to 12, wherein it is mixed with polymer 5 to 40% by weight, based on the weight of the heterophasic copolymer, of An additional elastomer. 23. A process according to claim 22, in the that said additional elastomer is ethylene rubber: propylene or plastomer 24. A process according to any one of the claims 1 to 23, further comprising: iii) forming said heterophasic polypropylene copolymer in a chosen article Among: films, molded parts, sheets, caps, bottles, fibers, tubes, foams, cable sheaths, insulators, retarders of flame and other high load compounds.